help with grep the pattern

I have those lines in a file:

:startStr xxxxxxx(anything) STRING1 xxxxxx
startStr xxxxxxx STRING1 xxxxxxxxxxxxx
startStr xxxxxxxxx STRING2 xxxxxxxx
.......

grep only the lines starting "startStr" (without ":") & with "STRING1"
-e.g. the second line in the above file

I use the following which works but how to also include the "startStr"??
grep '^[^:]*STRING1' *

Thanks!!

Better of with a sed solution

sed -n -e "s/^startStr.*STRING1.*$/&/p" input.txt

grep-wise this may work.

grep -e "^StartStr.*STRING1" input.txt

thanks vino!!
Both work, with a little mod (on SunOS)- the " " => ' ', & leave -e out of the grep.